[lintstaged] Add Jest tests to .lintstaged.js

Summary: Run lib and keyserver tests for the same conditions that flow is run in those directories.

Test Plan:
Proof that the tests run:

Reviewers: jacek, abosh, varun, tomek

Reviewed By: abosh, varun

Subscribers: ashoat, adrian

Differential Revision: https://phab.comm.dev/D4619